Sea level rise still a long-term concern
By Summit Voice
FRISCO — A post-Sandy study of the seafloor off the shore of New York and New Jersey showed that the protective barrier system that protects the coast from erosion stayed mostly intact, providing some re-assurance to property owners trying to rebuild.
But long-term concerns related to rising sea level remain, a group of researchers said last week, outlining their findings at the American Geophysical Union conference.
“The shape of the bedforms that make up the barrier system did not change a whole lot,” said lead researchers John Goff of the Institute for Geophysics. “Where we might have expected to see significant erosion based on long-term history, not a lot happened — nothing that ate into the shoreface.”
“The sand largely took the blow,” added Jamie Austin of the Institute for Geophysics. “Like a good barricade, the barrier system absorbed the significant blow, but held.”
But continued sea-level rise will create more pressure on the barrier system, heightening problems onshore. With higher sea level, all of the onshore impacts of a storm like Sandy will go up, Goff said.
“In the long-term, if sea level gets high enough, the barrier system has no choice but to retreat and move landwards,” he said. “Exposing the shoreline to increased erosion. “But at least for the present, there’s no evidence of that being imminent.”
The mission was the sixth rapid response science mission funded by the Jackson School of Geosciences at The University of Texas at Austin. The missions place geoscientists on the scenes of natural disasters as quickly as possible to measure the often vanishing traces of hurricanes, earthquakes, tsunamis and other disasters.
The findings are based on pre-storm survey data compared to post-storm data acquired through a collaborative rapid response science mission to the south shore of Long Island led by scientists at The University of Texas at Austin’s Institute for Geophysics, Adelphi University, Stony Brook University and other institutions in the New York metro area.
Long-term concerns remain about the effects on the region of sea-level rise, pollutants churned up by the storm within back-barrier estuaries, and the damage closer to shore, but in the near-term, Long Island residents can rebuild knowing that Hurricane Sandy did not significantly alter the offshore barrier systems that control coastal erosion on the island.
The survey team also found evidence the storm brought new pollutants into the waters off Long Island. Heavy metals were detected in a layer of mud that the storm deposited offshore. Beth Christensen of Adelphi University traced the metals back to muds from the South Shore Estuary Reserve, which has a long history of pollution from industry and human habitation.
By this summer, natural forces had dispersed the layer of mud offshore, and the concentrations of toxins were not high enough to be an immediate concern, said Christensen.
“But if we continue to see more events like Sandy, we’ll see the introduction of more and more muds from the estuary,” said Christensen, “adding additional toxins to an already stressed system.”